Patent GB-694306-A (GB)
Title: Improvements in or relating to electrical signalling systems for rail traffic control
Inventor: PREIST THOMAS PHILIP
IPC: B61L1/20
Filed: 1949-04-20
Abstract: 694,306. Railway signalling systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. April 20, 1950. [April 20, 1949] No. 10438/49. Class 105. A signalling system for railways such as a mine haulage system with individual locomotives has two or more identical control units each comprising a set of relays such units receiving signals as the locomotive passes points along the track and being so interconnected that on passage of a locomotive it is either immediately given a clear signal to proceed or if there is a conflicting movement, such as on a crossing line, the signal of the arrival of the locomotive is stored and subsequently a clear signal to proceed is given when the conflicting movement is past. In the latter case the locomotive is given a signal denoting that its arrival has been stored. The arrangement is also adaptable to protect the vehicle against an oncoming one in the rear. Fig. 4 shows the arrangements for a double tracks crossing, Fig. IE. Four relay assemblages, Group 1 ... Group 4, have their sets of terminals 1 ... 13, 24, 25, 27, 28 interconnected as shown by the dotted lines. Contacts D1 ... D4 respectively are closed by an approaching locomotive on track 1, 2, 3 or 4. Contacts C1 . . . C4 respectively are opened by a departing train on track 1, 2, 3 or 4. An approaching locomotive on track 1 briefly closes contact D1 to energize relay 1D from the positive side of rectifier-source MR1 through terminal 6 contact D1 and terminal 7. Contact 1D1 of this relay picks up a relay 1L which thereafter is stuck up from terminal 5 over departure contact Cl, its own front contact 1L3. Contact 1L2 of relay 1L then extinguishes the red signal lamp R and lights the green proceed lamp G for track 1. On the conflicting tracks 3, 4 any locomotive approaching at this 'time while the first is proceeding along track 1 to the departure point would see an amber lamp A lit to denote that its approach had been registered but the red lamp R would still be lit. This is effected by the first locomotive on track 1 having caused at the front contacts 1L1 and 1L4 the energization of relays 3G, 4G. When therefore an approaching locomotive on track 3 or 4 closes contacts D3 or D4 and energizes relay 3D or 4D the contact 3D1 or 4D1 thereof now picks up a storage relay 3S or 4S over front contact 3G1 or 4G1 and thereafter the storage relay sticks up until the departing train on track 1 opens contacts C1 to break the stick circuit of relay 1L whereupon the opening of front contacts 1L1 and 1L4 drops the relays 3G and 4G. Contact 3G1 now being on its back point causes relay 3L to be picked up over front contact 3S1 of the relay 3S before this slow relay drops such contact. Front contact 3L2 then lights the green lamp G for track 3 while the amber light A which was lit over front contact 3S2 becomes extinguished. For protection against an oncoming locomotive at the rear a similar interconnection of the relay assemblages is used whereby a rearward assemblage has its guard relay 1G picked when the first locomotive causes the operation of relay 1L and such relay 1G remains stuck up until the locomotive reaching an ahead section point opens the contact C2, Fig. 5 (not shown). The guard relay 1G causes a rearward approaching train to receive an amber signal (denoting its arrival registered) but with the red lamp lit. The contacts operated on the passage of the locomotive may be actuated manually, by a track treadle, or by a photoelectric arrangement.